The invention concerns a tuyere arrangement for the introduction of agents into a molten bath. The invention further concerns a method of operating such a tuyere arrangement.
German Publication No. DE-C2-38 09 828 discloses a tuyere arrangement of that kind. The known arrangement for the introduction of gases and/or solid reagents and additives into a metallurgical smelting vessel includes an apertured block or brick which is fitted into the wall of the vessel and which axially slidably accommodates a scavenging or flushing block having at least one gas duct which can be connected to a gas conduit. The outlet opening of the gas duct is provided at the peripheral surface of the scavenging or flushing block so that the outlet opening is exposed and the agents can be introduced into the molten bath only when the scavenging or flushing block has been advanced with its inner end beyond the annular end face of the apertured block. Withdrawal of the scavenging or flushing block guarantees a closure effect, without the necessity of applying a continuous gas pressure to the scavenging or flushing system, so that the tuyere arrangement is particularly suitable for transportation vessels such as a ladle, in regard to which it is not possible for the gas scavenging or flushing system to be supplied with gas over the entire residence time of the molten material in the vessel. Accordingly axial displacement of the scavenging or flushing block serves to provide that it can be used not only for the introduction of agents but also as a closure member.
German Publication No. DE-C-23 24 086 discloses a tuyere for the introduction of refining gas, in particular oxygen, through the wall of a refining vessel, beneath the surface of the bath, wherein the refining gas is passed into the molten bath through an inner tube and a protective agent is passed into the molten bath through a concentric outer tube, and the two tubes are arranged concentrically in a stationary casing tube. The inner and the outer tubes are axially displaceable and interchangeably arranged at respective spacings in at least one casing tube.
That arrangement provides at least one additional annular space for the introduction of a protective agent and it affords the possibility of changing or axially displacing the inner and the outer tubes between two batches in order to deal with brickwork wear in the immediate vicinity of the tuyeres. Thus, in the case of a funnel-like configuration being formed by wear in the region of the outlet opening of the tuyere arrangement, the inner and outer tubes can be advanced and then the funnel configuration can be filled up for example by spraying or plugging.
European patent publication No. EP-B1-0 182 965 discloses a method of protecting a tuyere comprising at least three concentric tubes forming a central duct and at least two annular ducts, wherein an oxygen-bearing gas is injected through the central duct and a mist of atomised water is injected as a cooling fluid through an annular duct, atomisation of the water being effected by means of a carrier gas in a tuyere head at the entry side of the tuyere. That cooling fluid has proven to be particularly effective in regard to an increase in the service life of the tuyere.
In a tuyere arrangement for the introduction of agents into a molten bath, the object of the present invention is that of increasing the service life, reducing the down times and simplifying maintenance operations. The invention further seeks to provide a method of operating that tuyere arrangement.